Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary...http://www.google.de/patents/US5742792?utm_source=gb-gplus-sharePatent US5742792 - Remote data mirroring
